Suppression of electromagnetic interference (EMI) has become a major concern in the transmission, reception, and processing of electronic signals and data. Modern communication systems are often designed as an interconnection of functional blocks and connections made using cables or wiring harnesses. Such interconnections often present opportunity for common mode current loops between devices that can lead to EMI regulatory failure.
Due to EMI concerns, Ethernet devices, such as Ethernet ICM transformers (ICMts), are often coupled with a common mode choke (CMC). A CMC can comprise two coils wound on a single core and may be useful for EMI and Radio Frequency interference (RFI) prevention from, for example, power supply lines and other sources. A CMC can pass differential currents (e.g. equal but opposite), while blocking common-mode currents. Thus, when properly operated, CMCs filter common mode currents without causing signal degradation. Therefore, the addition of CMCs, e.g., in conjunction with a connector such as an ICM, can provide filtration of mode currents, while also allowing passage of desired signals.
In some traditional configurations, CMCs and ICMs are bundled together, for example into a common ICM housing. By way of example, CMC and ICM components can be bundled into “pigtail” components, which provide connections between the CMC and ICM as well as a shared housing. Bundling of the ICM and CMC into the pigtail is a labor intensive process and makes it nearly impossible to later separate the ICM/CMC from the pigtail to make component modifications or adjustments.
For example, the ICM can include an Ethernet transformer that is configured (tuned) to block ground currents, e.g., of a corresponding Ethernet transceiver or “PHYreceiver.” In contrast, the CMC is generally tuned to filter noise produced by other device components in which the ICM is disposed. Because noise resulting from the other components can vary with the life of the device, or as device changes are made, it is not uncommon to require re-tuning of the CMC. To simplify the ability to tune/re-tune the choke, some Ethernet implementations provide physically decoupled CMC and ICM modules (as opposed to pigtails in which the respective components cannot be easily decoupled).
In such configurations, separate CMC and ICM components are physically separated but electrically coupled, for example, via a printed circuit board (PCB). The physical decoupling of CMC and ICM components can provide the groundwork for several advantageous modifications to conventional CMC and ICM architecture.